Continuous, twenty-four hour or longer, electrocardiogram (EKG) monitoring (Holter) systems are widely used in the prior art for diagnosing heart disease. However, the long term prior art EKG systems are concerned only with EKG signals which is a major shortcoming.
There is another much simpler diagnostic means used in the prior art, namely the brief exercise "stress test" in which the EKG signals are recorded during a brief time interval while the patient is exercising strenuously, for example, on a treadmill. However, this latter test is not comprehensive because exercise is only one of a number of stresses that can cause EKG abnormalities.
U.S. Pat. No. 4,830,021 which issued May 16, 1989 to the present inventor describes a locomotor activity monitoring system which includes EKG, and which involves long term monitoring of the patient. The system described in that patent, unlike other prior art cardiac monitoring systems, uses EKG only incidentally and primarily to monitor heart rate.
There are shortcomings in each of the prior art systems referred to above. For example, the Holter System has no detection/recording capability other than time, EKG readings and a patient marker. The patient maintains a time related diary of such events. At best, this approach is qualitative. It is also incomplete, since no data is entered, for example, when the patient is asleep. In essence, there is no objective or recorded evidence of any patient activity.
The cardiac abnormalities which are revealed by the prior art cardiac monitoring systems are equated only to physical activities. However, such cardiac abnormalities may also be revealed by a number of other conditions in the body. Knowledge of these conditions, other than physical activity, which provide detectable cardiac abnormalities is frequently important for determining the proper treatment. As noted above, such knowledge can not be acquired from current cardiac monitoring systems and techniques, and it is an object of the present invention to provide a system which also monitors such other conditions in the body.
It is well known, for example, that inadequate blood supply to the heart may alter a portion of the EKG known as the S.T. segment. It is also well known that the most common cause of inadequate blood supply to the heart is partial closure of one or more arteries by fatty formations. Limited blood flow through a narrowed artery which is inadequate to meet the needs demanded by exercise is the most common cause of such EKG changes. However, normal or slightly affected arteries may produce the same effect due to spasms from emotional upsets which are transmitted to the heart by the nervous system, and which are not detected by the prior art cardiac monitoring systems. The treatment is the case of clogged arteries is normally surgery, but a vastly different treatment is required in the case of arterial spasm cause, for example, by emotional upsets in relatively normal arteries. It follows, therefore, that even the most elaborate and complex EKG recording and analyzing systems in the prior art are incomplete.